Concrete mixers, which include front-discharge mixers and rear-discharge mixers, typically include a rotatable mixer barrel that may be supported by a support structure and rotated by a suitable prime mover, such as a motor. Rotatable members are often coupled between the support structure and the rotatable mixer barrel to assist in the rotation of the mixer barrel relative to the support structure. The support members may include movable members for translating or adjusting an angle of the barrel relative to a frame of the concrete mixer, which is often mounted on or incorporated into a vehicle, such as a concrete mixer truck. A cab, which may include both vehicle driving controls and rotatable mixer barrel controls, is often located generally directly below a discharge opening of the barrel in a front-discharge mixer, and generally at an opposite end of the associated vehicle frame from the discharge opening in a rear-discharge mixer.
Internal structures in the barrel are configured to move concrete, often in an upwards spiral, towards the discharge opening of the barrel when the barrel is rotated in a first discharge direction. The internal structure also is configured to prevent the concrete from moving towards the discharge opening of the barrel when the barrel is rotated in a direction opposite the first discharge direction. Concrete exiting the barrel drops into a concrete collector that in turn directs the concrete into a flow direction chute and then to the job site.
During the flow of the concrete from the barrel to the collector, some concrete may not flow into the collector and instead may run down an external surface of the barrel. This is wasteful and also can contaminate the movable members and antifriction wheels that support the barrel as well as other parts of the concrete mixer. Errant concrete also can fall onto the driver's cab roof or windows affecting visibility.
In the conventional response, a wiper typically is mounted to the collector. The wiper is often made of rubber, is arcuate in shape, and may be about 6 to 8 inches wide. The wiper often has a free edge which bears against the barrel. The opposite edge is fixedly coupled to the collector. For example, the coupled edge of the wiper is pressed against the top edge of the collector by a curved steel bar that is held in place by a plurality of bolts that pass through the bar, through the wiper, and through the collector, and are secured via nuts.
The collector, and thus the wiper, is supported by a platform that in turn is mounted to the support frame of the concrete mixer. The platform is supported from the support frame at a location separate from a location of engagement of the antifriction wheels that support the barrel relative to the support frame.
The support frame flexes not only when the concrete mixer is moved over, such as driven over, uneven surfaces, but also because the load of concrete moves around inside the barrel as the barrel rotates. As the support frame supporting the mixer flexes in response to these forces, the open end of the barrel having the discharge opening moves with respect to the collector and the wiper, which may cause a limited amount of concrete to fall to a side of the collector rather than into the collector. Also, contact between the barrel and the wiper changes, with one part of the wiper being compressed and an opposite side being relieved of pressure. A constant flexing and compression of the wiper in this manner causes the wiper to wear and require replacement to avoid additional dribbling of concrete onto external surfaces of the barrel, such as down the underside of the barrel, or onto the cab. When the wiper is replaced, the plurality of bolts that secure it to the collector must be removed, which is a challenging procedure because the nuts and bolts are often difficult to reach and are often coated with cured concrete.